stty

   stty can be used to change terminal settings as needed, and has many
   uses.  Use 'man stty' for a full description.

      stty erase ^H                  ^H will now act is backspace

yes

   yes may seem useless at first, because all it will do is repeat the word
   'yes' (or any argument you give it) as fast as it can.  However, in case
   a particular program requires the user to answer 'yes' to a long set of
   questions, it can be helpful, as in:

      yes | survey

biff

   Named after a programmer's dog who would bark when the mail arrived.
   This program will interrupt whatever else is running the moment any
   new mail arrives.

      biff yes                activates biff
      biff no                 turns it off

write/talk

   These programs are basically self-explanatory.  An important detail,
   however, is that other users can be denied the ability to send text
   to your screen.

      mesg n                  you can't be disturbed by talk or write
      mesg y                  talk requests and text will come through

clear

   Clears the screen.  On many systems, control-L does this too.

script

   Records all text that appears on the screen, and saves it to a file called
   'typescript'.  The script will continue until it receives a ^D or 'exit'
   command.

nohup

   Used to allow a program to run, even after the user logs out.  Output
   from the program will be saved to the file 'nohup.out'.

lpr

   Line PrinteR.  Will attempt to print a file to the UNIX system's line
   printer.  Note that this cannot be reconfigured to print to a local
   machine.

lpq

   Line Printer Queue -- show status of printer.

ssh

   Secure Shell.
   Use to connect to another machine using encryption.  Useful when
   working on a group of related machines.

tar

   archives files and directories.  Most common usage:

          tar -xvf stuff.tar      Extracts files from 'stuff.tar'

gzip

   compression program, very commonly used.  Can decompress files with
   a .gz or .Z suffix.

          gzip -u file.gz        Decompresses 'file.gz' into 'file'

gcc

   C compiler.  Compiles and links C code into object files and executables.

	  gcc myfile.c		         Compile into a.out
	  gcc myfile.c -o myfile         Compile into myfile
	  gcc myfile.c -o myfile -lm     ...and link with math functions

Not all of these commands are used frequently, and some are redundant, but
the commands outlined here are enough to allow a person to be extremely
efficient (not to mention comfortable) in UNIX.  Use this as a reference, when
needed, and work towards learning what most of these commands do.  All of them
are useful, so knowing them can't hurt, if you have the time.  For more
complete information about any of these commands, use the 'man' command.

Courtesy of Aaron Gage